Electrical connector



Dec. 6, 1949 N. A. TORNBLOM ELECTRICAL CONNECTQR Filed Spt. 13, 1946 mns ZHw-ombaw g 1f WW m \m Patented Dec. 6, 1949 UNITED ST-AT ELECTRICAL CONNECTOR Nils A. Tornblom, Chicago, 111., assignor to Appleton Electric Company, Chicago, 111., a corporation of Illinois Application September The present invention pertains generally to electrical connectors, and more particularly to that type of connector through which armored or unarmored electric cable is led to anoutlet box or similar fixture.

One object of the invention is to provide a novel and inexpensive electrical connector which will lend itself to easy and rapid installation.

Another object is to provide a connector in which the turning of a single screw simultane ously clamps the cable firmly to the connector and locks the latter securely to the outlet box,

A further object is to provide a connector which: will be susceptible of ready application to a cable which has already been installed, without removal of the cable end from the outlet box.

Further objects and advantages of the invention will become apparent as the following de- 13, 1946, Serial No. 696,775

Claims. (o1. ass-ts) carries a clamping screw H and an adjustable clamping bracket I2 which cooperate with the lower half shell in a manner to be pointed out H below in, gripping the inserted portion of a cable.

.previously been commonly employed in conscription proceeds, taken in connection with the,

accompanying drawings, in which:

Figure 1 is a section through a conventional outlet box, showing a connector embodying the present invention installed in such box and the end of a connected cable.

Fig. 2 is a view similar to Fig. 1, the cable and a portion of the box having been omitted.

Fig. 3 is an enlarged end elevation of the connector, taken from the outer end.

Fig. 4 is an enlarged longitudinal sectional view of the connector.

Fig. 5 is a transverse sectional view taken substantially along the line 5-5.in Fig. 2.

Fig. 6 is an end view of the device as illustrated in Fig. 2 showing the inner end only, the remaining portion having been omitted.

Fig. '7 is a longitudinal sectional view of the connector, but showing the same equipped with a ferrule used to adapt the device to armored cable.

Although a particular embodiment of the invention has been illustrated and described in some detail there is no intention to thereby limit the invention to such embodiment, but on the other hand, the intention is to cover all modifications and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims.

The connector shown in the drawings, and

which constitutes an illustrative. embodiment of the present invention, has a body I comprising complemental upper and lower half shells or sections 2 and 3 held together by a resilient split ring 4. One end of the body is tapered, forming a forward nose portion for insertion into an opening in an outlet box. The upper half shell nectors.

The upper half shell 2 is constituted by two integral'portions 5 and l of slightly different size. The portion -5'is generally U-shaped in cross section, the curved bottom of the U being formed by dishing the shell outwardly to accommodate one'arm of clamping bracket l2. The side elements of the U are each formed by parallel areas having laterally oiiset parts which make up guiding lugs 6. The lateral ofisets are produced by two shallow concave indentations running longitudinally of portion 5 for the purpose of stiffening shell 2 against bending stresses resulting from reaction against clamping screw ll. Lugs 6 provide lateral guiding means for the lower half shell 3 in its movement relative to the upper half shell. Dished portion 5 also includes a centrally located tapped hole for clamping screw ll,and a transversely running slot for a clamping bracket 12.

The tapered portion 1 of the upper shell 2 is of substantially semicircular cross section, gently necking down from a larger diameter adjacent to portion 5 to aslightly smaller diameter at the end of shell 2. Near its outer end, the portion 1 is provided with a peripheral groove 8 of suitable shape to accommodate a split snap ring l which is mounted therein. At the inner end of the portion I, immediately adjacent to the portion 5, a relatively wide, circumferentially extending groove or indentation 9 of rectangular cross section is fashioned. This groove, which does not extend completely around the external surface of the half .shell, is adapted to engage the side wall of theoutlet box, and, in cooperation with a corresponding groove 9a. in the lower half shell, to lock the connector with respect to the box.

The internal surface of the upper half shell 2 follows a contour generally reflecting that of its outer surface, resulting in the formation of an internal shoulder in the inner surface of the tapered portion. From the internal shoulder toward the snap ring end, the inner surface assumes a frusto-conical or inwardly tapering shape until it joins an internal lip 13. This lip, which-runs in a circumferential direction, coop- 3 erates with a corresponding lip l3a in the lower half shell to form an internal annular bead. Although more fully described below, it may be noted that the bead and inwardly tapering surface serve to locate the split ferrule 22 which modifies the device for use with armored cable.

Both half shells present opposed surfaces l4 and Ma, which are symmetrical up to the point where the surfaces l4 intersect the edges of the lugs 6. These surfaces are defined on each shell by two planes intersecting at an obtuse angle with its vertex located a short distance from the tapered ends of the shells. Neither plane ispar: allel to the longitudinal center line of the con; nector. This construction predu'ces' fulcrum points intermediate the tapered end of the body I and a plane passing through the external grooves 99a transversely .of the body, :and insures sufficient clearance at both shell ends to permit fore and aft rocking movement of'one' shell upon another.

The lower half shell 3 includes a tapered portion la and a necked down portion 15. The former is practically identical, both externally and internally, to portion '1 of the upper half shell, already described. The latter is simply an extension of reduced outer diameter and generally arcuate in cross section. "The internal surface of portion I5, corresponding substantially to its external one, includes a centrally located projection 16 designed to grip the electric cable inconjunction with arm I8 of the clamping bracket I2.

Cable clamping means, comprising the screw II and bracket [2, are carried bythe upper half shell 2. The bracket I-2 consists of a sheet metal strip bent in the form of a wide U with' upper and lower arms I! and [8. A holeslightly larger than the diameter of screw H is provided in the arm I! for the dual purpose of guiding 'the bracket for limited sliding movement in the slot -'I 0 'and for preventing removal of'thebracke't from the slot. Arm l8, of slightly greater width than the remainder of the bracket, carries a wedge shaped projection on its under side forming" a shoulder l9 which cooperates with projection P6 in the lower shell to oppose the withdrawal of cable from the connector. The indentation inthe opposite side of arm 18 corresponding-to the w'edge shaped projection serves to center the arm on theendofscrew ll.

' In order to position the arm 48 upon the cable to be clamped, and to eliminate any'tendency to slip ofi, the two side areas of excess widthare bent downwardly through a convenient acute angle toward the lower half shell; As a further precaution against removal" ofbracket I! from the slot, the end of screw H is peened over s 'ufiiciently to prevent it from being completely withdrawn from the tapped hole in shell'2.

In normal use, the tapered end of the connector is inserted into a hole in the side of an outlet box 20 and an axial force is applied. The re silient action of split ring 4 will permit the half shells to be compressed by the'action of the edges of the hole on the tapered portions, until these edges snap into engagement'with locking grooves 9 and 9a. An electric cable '2-l is then pulled through the connector to the position shown in Fig. 1. The final step in installation consists of tightening the screwxll, which urges bracket [2 into clamping engagement with the cable. The force exerted by the screw produces a simultaneous equal and opposite reaction tending to push the half shells apart, expanding, the connector to the point where grooves. Q and. 8a

are pressed firmly against the edges of the hole in box 20, positively locking the connector in place.

It will thus be appreciated that the connector illustrated lends itself to rapid and simple installation, the only tool needed being a screwdriver. Moreover, the tightening of a single screw secures the cable in the connector and locks the connector to the box. Use of the usual lock nut for securing the connector in place is obviated, thereby eliminating its cost and the time consumed in its application.

Fig. .7 illustrates a modification adapting the connector for use with armored cable. A split ferrule 22 is forced into the tapered end of the connector where it is engaged by the annular bead formed by lips l3 and I3a and the inwardly tapering frusto-conical surface described above. The end 2la of a B-X cable or similar armored cable'r'n'ay be inserted into the connector until its armor abuts the inner edge of the ferrule. By this means, it becomes possible to lead the insulated conductors over a smooth surface, with no danger of chafing upon the jagged edges of the armor.

In certain instances, it may be desirable to have the cable movable in the opening of the outlet box wall until its ends have been electrically connected. The present invention finds a ready application to cases of that type. By virtue of its split construction, the connector may quickly be disassembled and then reassembled on the cable without removing the latter from the box.

'I claim as my invention:

1. An'electric'al connector for cable comprising, in combination, a body including a complemental pair of half shells presenting exterior indentations intermediate their ends for reception of the edges of ahole in an outlet box in which the connector is inserted, a resilient snap ring encircling "said shells adjacent one end thereof t'o' retain the same in assembled opposed relation while permitting'their opposite end portions to be spread apart, and means including a transversely extending screw threaded in one of said half shells adjacent said opposite end thereof for clampingly engagingan inserted cable end simultaneously spreading said half shells as the screw is threaded inward to thereby engage said indentations with the, edges of a hole in an outlet-box."

2 A connector for electric cable having, in combination,' a'body comprising two half shells, resilient means for urging said half shells together, adjustable clamping means carried by one of said shells and adapted simultaneously to clampa length of 'cable within said body and-to urge said hal-f' shells outward away from each other into engagement with the encircling margins of hole in'which said body is inserted.

"3. A connector for electric cable adapted to be snapped into position within an opening in an outlet box upon being thrust axially into the same, said-connector comprising, in combination, a body split longitudinally into two half sections having substantially coplanar circumferential grooves intermediate their ends, saidbody tapering axially from said grooves toward one end thereof, said sections being adapted to rock fore and aft relative to :each other about fulcrum points located between the plane ofthe grooves and the tapered endpof said body, resilient means for yieldably urging said sections to rock about said fulcrum points into. a .position in which the outer end 731 portions. of saidsections-are spread apart, said resilient means being adapted to act on, said sections in opposition to wedging action occurring between the tapered portion of said body and the margins of the hole as said body is thrust axially into the hole.

4. A connector for electric cable adapted to be snapped into position within an opening in an outlet box upon being thrust axially into the same, said connector comprising, in combination, a. body tapered axially toward one end to form a. forward nose portion and split longitudinally into two complemental half sections having opposed edges, said sections having coplanar external circumferentially extending grooves intermediate their ends for engagement with the margins of a hole in an outlet box or the like when said body is thrust into such hole, coacting fulcrum points formed in said opposed edges 5. A device for connecting armored electric cable to an outlet box or the like through an opening in the wall thereof, having, in combination, a tapered body split longitudinally into two complemental half shells and provided with an internal annular head at one end located outwardly of an internal shoulder, a resilient split ring encircling said one end of said body and urging said half shells together, a split ferrule located immediately inside said one end of said body on said bead to form a stop for the cable armor, and clamping means mounted on one of said half shells and arranged to simultaneously clamp said cable within said body and to expand said half shells away from each other into locking engagement with the margins of an opening in which said body is inserted.

NILS A. TORNBLOM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 18,634 Thomas Oct. 18, 1932 1,885,228 Buchanan Nov. 1, 1932 

